Bunker and spiral chute loading means



Cct. 11, 1966 R. c. STOTT BUNKER AND SPIRAL CHUTE LOADING MEANS 2 Sheets-Sheet 2 Filed. Nov. 5, 1964 FIGB.

I NVEN'roR S'roTT ROBERT C United States Patent O 3 278,054 BUNKER AND SPIRA CHUTE LADING MEANS Robert C. Stott, 12 Westfield Road, Dudley, England Filed Nov. 5, 1964, Ser. No. 409,083 Claims priority, application Great Britain, Nov. 7, 1963, 44,065/ 63 Claims. (Cl. 214-17) This invention has reference to bunkers for use in the bulk storage of coal, 'coke or other material cons-isting of a mixture of pieces o-f which the dimensions are included in a range having predetermined upper and lower limits, and which tend Ito break down or degradate, and the larger pieces tend to segregate from the smaller pieces, when the material is being charged into or discharged from a bunker.

In an attempt to reduce such tendency for the pieces of pre-graded coal, 'coke or other material to degradate and segregate, it is known practice to provide a bunker into which the material is to be charged, stored and subsequently discharged, with a sloping floor having a shutter or door controlled discharge throat, and lto install vertically within the bunker, iirst, a chimney which is located centrally of the bunker and comprises two parallel channel section members arranged with their mouths adjacent to but spaced apart from one another and, secondly, a spiral chute which is `located between Athe chimney and one wall of the bunker and into the upper end of which the material is fed when the said material is being charged into the bunker. Upon being fed into the upper chute end, the material travels down the chute and, if the bunker is empty, is transferred initially from the lower end of the chute on to the bunker iioor and piles up on the floor until it reaches the lower end of the chute. As the charging operation proceeds the lower end o-f the chute is embedded in the material which thereafter, upon reaching the top of the pile, spills from the chute to the interior of the spiral and is then transferred to the interior of the bunker through a transfer zone which travels upwardly of and around the spiral as the depth of the pile increases. The chimney also becomes embedded in the material as the depth of the pile increases and pieces of material from the top of the pile flow into and fill the interior of the chimney through the clearances between the adjacent edges of the sides of the channel section members. As the material is transferred from the chute to the bunker, the upper surface of the pile assumes a conical formation of which the -top is located within and coincides with almost one complete convolution of the spiral. However, since the chute is located laterally of the chimney, it is spaced considerably further `from one of at least two opposed walls of the bunker than from the other so that the length of the cone shaped upper surface of the pile varies from a minimum to a maximum around the chute and, consequently, some of the pieces of material transferred to the longer portion of the said surface will travel through a greater distance than any of the pieces transferred Ito the shorter portions and will be subjected to a correspondingly lg-reater degree of degradation and/or segregation.

The principal object of the present invention is to overcome this disadvantage in a simple and economical but eicient manner.

In accordance with the said invention, a bunker for use in the bulk storage of material consisting of pieces Mice which are of dilerent dimensions and are liable to degradation and/o-r segregation when being charged into or discharged from the bunker, is provided with a vertical chimney which is disposed within and co-axially of the bunker and comprises a spiral chute and a spiral curtain, the curtain being concentric to the chute and being formed with at least one spiral and co-extensive slot of a constant predetermined width, and the convolutions of the curtain alternating with the convolutions of the chute longitudinally of the chimney.

In order that the invention may more readily be understood and carried into practice, reference will now be made to the accompanying drawings wherein:

FIGURE l is an elevation, partly in section and partly diagrammatical, of a storage bunker.

FIGURE 2 is a section, on an enlarged scale, along the line n n, FIGURE 1.

FIGURE 3 is an elevation, similar to but on a smaller scale than the elevation of FIGURE l, of the lower part of the bunker and shows material being charged into the bunker.

FIGURE 4 is an elevation similar to the elevation of FIGURE 3, but shows material being discharged from the bunker.

FIGS. 5 and 6 are sectional views similar to FIG. 2 |but of different embodiments, and t FIG. 7 is a fragmentary elevation view of still another embodiment.

The body 1 and oor 2 of the storage bunker shown in the drawings, may be of any known and suitable construction and, consequently, are illustrated in diagrammatic form only. The body is preferably rectangular in plan and the floor tapers inwardly and downwardly from the lower end of the body and is formed with a central discharge throat 3; the lower outer end Yof the throat is adapted to be opened and closed Iby a shutter 4 which, again, is illustrated in diagrammatic form only since it may be orf any known and suitable construction; further, although Vas illustrated, the shutter is provided with a counterbalance 5 and is adapted to be swung from and to its throat-closing position by a handle 6, it is to be under stood that any other alternative means for operating the shutter may be adopted.

A cylindrical chimney 7 is carried within and co-axially of the bunker vertically `above the throat 3. The chimney comprises a spiral chute 8 and a spiral curtain 9 of which each convolution extends upwardly from and is welded or otherwise secured along its lower edge to, the upper edge of a corresponding yone `of the convolutions of the chute. The depth of each convolution of the curtain is such that its upper edge is spaced from the lower edge of the next adjacent upper convolution of the chute so that `a spiral slot 10 of a constant precalculated width is formed in and extends from the top to the bottom of the curtain.

Preferably the curtain is fabricated from a steel or other metal band and the chute is built up from a number oaf cast metal sections which are of channel section and are welded lor otherwise secured permanently together end to end in such a manner that, as shown in FIGURE 2, the mouth of the chute opens to the interior of the chimney, and the lower edge Iof the chute is located radially inwards of its yupper edge.

The width and pitch of the slot varies according to the dimensions of the largest pieces in the material to be stored in the bunker and are such that when any portion of the chimney is surrounded by and is submerged in a pile of material stored in the bunker, the slot in that portion will be bridged by the material although the pieces of material on the top of the pile are able to flow freely through the slot either from the interior `of the chimney into the interior of the bunker when the material is being -charged into the bunker, or from the interior of the bunker to the interior of the chimney when stored material is being discharged through the throat 3. For this purpose the width of the slot is precalculated so that at any position along the slot, the length of a line x extending between and perpendicularly to the edges of the slot does not exceed ten times the maximum dimension lof the said largest pieces, whereas the horizontal distance between the edges is not less than ten times the said maximum dimension. Further the pitch of the spiral chtite is precalculated so that the material to be charged into the bunker will travel down the chute at a speed of, or in the vicinity of eight :feet per second.

The chimney is supported within the bunker by a `framework 11 which may be of any desired construction; for example, as illustrated diagrammatically in FIGURE l, the framework may comprise vertical channel bars 12 which 4are spaced equidistantly apart around and externally of the chimney and of which the lower ends are fixed to the internal surface of the Hoor 2, tie bars 13 which extend between and are fixed to the chute and the vertical bars, and additional tie bars 14 which extend between and fixed to the curtain and the vertical bars. If desired, the upper part of `the framework may be anchored to the body 1 by horizontal tie bars (not shown) extending between and lixed to the vertical bars of the body walls.

The lower edges of the bottom convolution of the chute and of the bottom convolution of the curtain are spaced from the floor 2 by a distance which is not less `than the Width ofthe slot.

The upper end of the spiral curtain is located bel-ow the top of the bunker body, the spiral chute extends upwardly beyond the curtain end, and the upper end of the chute is fixed to the lower end of a straight inclined trough 15 which projects through the body top and of which the upper end is fixed to a hopper 16 adapted to deliver material transported to and `fed into the hopper by an endless belt 17 or any equivalent and known type orf conveyor, to and along the trough into the upper end of the chute.

The material entering the upper end of the chute slides down the chute and, if the bunker is empty, is transferred from the lower end of the chute onto the bunker floor; initially Ithe transferred material flows down the floor into the throat but, as the transfer 4of material from the chute into the hopper continues, the material first of all fills the throat and then piles up on -the bunker floor until the lower ends of the chute and curtain are embedded in the material whereafter, upon reaching the top of the pile, the material travelling down the chute spills from the latter into the interior of the spiral `and is then transferred into the bunker through a transfer zone of the `slot which, at any one instant, is located in the :angle formed between the top of the pile and the lower edge `of the chute portion projecting from and adjacent to the pile, but travels upwardly and around the lower edge of the chute as the depth `of the pile increases. As a consequence, and as shown in FIGURE 3, the surface of the top of the pile, at least at and in the vicinity of the chimney, coincides with almost one complete convolution of the chute and, circumferentially `of the chimney, falls from the zone of transfer along lthe lower edge of the convolution; however, between the chimney and the bunker walls, the surface of the pile is inclined downwardly at a substantially constant angle to the horizontal.

When, as shown in FIGURE 3, the shutter or door 4 is actuated to open the discharge throat 3, the material t within the bottom of the bunker flows into and down the Ithroat, is replaced by material flowing through the bottom of the chimney, and the material owing from the chimney is replaced by the transfer of material from the top of the pile through a transfer zone of the slot only because the portion of the slot in the embedded lower portion of the chimney is bridged by the pieces of material in contact with the chimney. As the discharge continues, the top of the pile is lowered, the zone of transfer travels down and around the slot and the surface of the pile assumes an inverted conical formation although at and in the vicinity of the chimney it again coincides with almost one complete convolution of the slot.

Since the material is charged into the bunker down the spiral chute and, both during the charging and discharging operations, is transferred `between the interior of the chimney and bunker only at the surface Vof the piled material, degradation yof the pieces is reduced to a minimum; further since the chimney is located co-axially of the bun-ker, the tendency vfor the larger pieces to segregate from 4the smaller pieces when flowing on to or lfrom the top of the pile, is also reduced to a minimum.

If desired instead yof forming the spiral slot between the upper edge of the curtain and the lower edge of the chute, the slot may be formed either between the lower edge of the curtain and the upper edge of the ch-ute as shown in FIG. 5, or, if desired, at any desired position between the upper and lower edges of the curtain as illustrated in FIG. 6. Further, if so desired and as shown in FIG. 7, the chimney may be provided with two identical spiral chutes of which the upper inlet ends are spaced apart by circum-ferentially of 'the chimney and are connected respectively to the hopper 16 by branch troughs 15, and may be formed with two identical spiral slots 10 of which the upper ends are 'also spaced apart by 180 circumferentially of the chimney.

I claim:

1. Apparatus for the bulk storage `of materials including a mixture of pieces of different dimensions which are liable to degradati-on and/or segregation when being charged into or discharged from the apparatus, comprising a bunker having an axis, a spiral chute and a spiral curtain secured to each other and together forming a tubular chimney havin-g la rectilinear axis and disposed within and substantially coaxial with said bunker, the convolutions of said curtain alternating with the convolutions `of the chute longitudinally of the chimney, said curtain being a band wound in a spiral concentric with said chute, and said chimney including at least one spiral slot of a constant predetermined Width and coextensive with said chute for communicating the exterior with lthe in'- terior of said chimney.

2. Apparatus according to claim 1 wherein said curtain forms a cylindrical wall of said chimney substantially parallel to said axis of the bunker.

3. Apparatus according to caim 2 wherein said bunker axis is substantially vertical.

4. Apparatus according to claim 2 wherein the mouth `of said chute opens to the interior of the chimney, and the lower edge of the chute is located radially inward of its upper edge.

5. A bunker as claimed in claim 2 wherein the slot is formed between the upper edge of the curtain and the lower edge of the chute. Y

`6. A bunker as claimed in claim 2 wherein the slo is formed between the lower edge of the curtain and the upper edge of the chute.

7. A bunker as claimed in claim 2 wherein the slot is formed between the upper and lower edges of the curtain.

8. A bunker as claimed in claim 2 wherein the chimney comprises two identical spiral chutes and the curtain is formed with two identical spiral slots, the upper ends of the chutes and the upper ends of the slots being spaced apart Iby 180 circumferentially of the chimney. v

9. A bunker as claimed in claim 2 the slot width and pitch is such that, at any position along the length of the slot, the length of a line extending between the perpendicularly to the edges of the slot does not exceed ten times the maximum dimension of the largest pieces of the material, and horizontal distance between the said edges is not less than the said maximum dimension.

10. A bunker as claimed in claim 2 wherein the lower ends of the chute and curtain are spaced from the bottom of the bunker by a distance not exceeding the slot Width.

6 References Cited by the Examiner UNITED STATES PATENTS 1,050,272 1/1913 Hamilton 214-17 FOREIGN PATENTS 469,717 l/l937 Great Britain.

GERALD M. FORLENZA, Primary Examiner.

R. G. SHERIDAN, Assistant Examiner'. 

1. APPARATUS FOR THE BULK STORAGE OF MATERIALS INCLUDING A MIXTURE OF PIECES OF DIFFERENT DIMENSIONS WHICH ARE LIABLE TO DEGRADATION AND/OR SEGREGATION WHEN BEING CHARGED INTO OR DISCHARGED FROM THE APPARATUS, COMPRISING A BUNKER HAVING AN AXIS, A SPIRAL CHUTE AND A SPIRAL CURTAIN SECURED TO EACH OTHER AND TOGETHER FORMING A TUBULAR CHIMNEY HAVING A RECTILINEAR AXIS AND DISPOSED WITHIN AND SUBSTANTIALLY COAXIAL WITH SAID BUNKER, THE CONVOLUTIONS OF SAID CURTAIN ALTERNATING WITH THE CONVOLUTIONS OF THE CHUTE LONGITUDINALLY OF THE CHIMNEY, SAID CURTAIN BEING A BAND WOUND IN A SPIRAL CONCENTRIC WITH SAID CHUTE, AND SAID CHIMNEY INCLUDING AT LEAST ONE SPIRAL SLOT OF A CONSTANT PREDETERMINED WIDTH AND COEXTENSIVE WITH SAID CHUTE FOR COMMUNICATING THE EXTERIOR WITH THE INTERIOR OF SAID CHIMNEY. 